How popular is Ephie?

Ephie is an uncommonly occurring first name for females. Ephie is an equally unusual surname for both adults and children. (2000 U.S. Census)

Which version is better?

with its source forms and related girl names. Euphemia, Eppie and Effie are the prominent variation forms of Ephie (not ranked). Adoption of these forms of Ephie was widespread during 1880-1889 (adoption of 0.27%), but now, the version Effie has fallen out of fashion. (Top 2000 Names, 2015)